Wealth & Wellness

A 5-minute read on what watching the market every day charges you, billed once in returns and again in sleep.

On any given day, a diversified portfolio is up only slightly more often than a coin flip. Stretch the window to a year and the odds of seeing a gain climb toward three in four. Same holdings, same returns; the only thing that changed is how often you looked. And because losses register roughly twice as strongly as equivalent gains, the daily checker doesn’t just see more red days. They feel hundreds of losses a year that the quarterly checker never experiences.

That feeling has a price with a name: myopic loss aversion. In experiments, people shown their returns more frequently allocate more cautiously and fiddle more. Outside the lab, Barber and Odean’s classic study of tens of thousands of brokerage accounts found the most active traders trailed the market by several percentage points a year. Checking sits upstream of trading: every look is a small invitation to do something, and doing something is where the returns tend to leak out.

The second bill clears overnight. Financial worry is one of the more reliable correlates of poor sleep, and the last portfolio check of the day tends to happen in bed. A red number at 11 p.m. changes nothing about the portfolio, but it can change the night. Short sleep then raises next-day impulsivity, which feeds the checking and the fiddling. The two costs aren’t separate line items; they compound each other.

Worth noticing: the app is not neutral. A brokerage home screen (pull to refresh, color-coded, one number that moves) borrows its mechanics from machines engineered for repeat visits, not for returns.

The experiment: one week, one scheduled look. Pick a time that isn’t bed (say Friday after lunch), move the app off the home screen, and jot two things nightly: how you slept, and whether you felt the urge to trade. The portfolio won’t notice the change. The observer usually does: same holdings, but most of the losses now happen unwitnessed.

P.S. Tomorrow: a 30-day experiment in deleting one food-delivery app: what it does to your budget and your bloodwork.